Material disappears while object is deselected
From the screenshots it appears you're seeing the OpenGL masking effect. 

The pink container's outer walls are semmi transparent and masking the portion of gray plate that's behind it. 

Parent the outer container to the gray plate then unparent it again.  (child = pink container) 

If that doesn't fix it, try ticking/unticking both objects' "Transparency" box. That's in the properties (cube icon) at right, way down to the "Display" tab.